A023588 a(n) = sum of exponents in prime-power factorization of 2*prime(n)-1.

1, 1, 2, 1, 2, 2, 2, 1, 3, 2, 1, 1, 4, 2, 2, 3, 3, 2, 2, 2, 2, 1, 3, 2, 1, 2, 2, 2, 2, 4, 2, 3, 3, 1, 4, 2, 1, 3, 3, 3, 3, 2, 2, 3, 2, 1, 1, 2, 2, 1, 3, 3, 2, 2, 4, 4, 2, 1, 2, 3, 2, 4, 1, 4, 4, 2, 1, 1, 4, 2, 3, 2, 1, 2, 1, 4, 3, 2, 3, 2, 4, 2, 3, 2, 1, 3, 3, 2, 2, 3, 2, 3, 2, 3, 1, 3, 3, 2, 3

Offset

1,3

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = A001222(A076274(n)). - R. J. Mathar, Mar 10 2011

Mathematica

Array[Plus@@Last/@FactorInteger[2*Prime[ # ]-1]&, 6! ] (* Vladimir Joseph Stephan Orlovsky, Feb 28 2010 *)
Table[Total[FactorInteger[2p-1][[;; , 2]]], {p, Prime[Range[100]]}] (* Harvey P. Dale, May 30 2024 *)

Crossrefs

Sequence in context: A067148 A035228 A035164 * A175242 A355770 A225843

Adjacent sequences: A023585 A023586 A023587 * A023589 A023590 A023591

Keyword

nonn

Author

Clark Kimberling

Status

approved